Adding user to new institution changes auth method for all users

[Robert Lyon]

When testing on master I did the following:

1) Upgrade an existing site from 16.10 -> Master

2) Checked the auth instance of all of the users (it was 1 = mahara / internal)

3) Created a new institution and added 'webservice' auth and deleted internal auth and saved

4) Checked the auth_instance table - there was only mahara/internal and newinstitution/webservice options

5) On admin user edit page I add a user to the new institution - they go from mahara/internal to newistitution/internal auth.

6) On checking the auth_instance table there is now a newinstitution/internal option - which is correct as the user will still need internal auth

But the problem comes when I check the usr table - all the users have this new newinstitution/internal option no matter what institution they are currently in

There is something wrong with adding user to institution

[Mahara Bot (dev-mahara)]

Patch for "master" branch: https://reviews.mahara.org/9046

[Mahara Bot (dev-mahara)]

Reviewed: https://reviews.mahara.org/9046
Committed: https://git.mahara.org/mahara/mahara/commit/6b1e661837a1737b0ab9d67750c320dada49a82d
Submitter: Cecilia Vela Gurovic (<email address hidden>)
Branch: master

commit 6b1e661837a1737b0ab9d67750c320dada49a82d
Author: Robert Lyon <email address hidden>
Date: Mon Aug 6 10:04:38 2018 +1200

Bug 1785514: Only update auth instance for this user

When we add a user to an institution that doesn't have internal auth
on the admin/users/edit.php page

behatnotneeded

Change-Id: I7395d1481b15c0e1e82eec0a61b3cca891df72f9
Signed-off-by: Robert Lyon <email address hidden>